Conventional methods of treatment of skin lesions have generally employed conventional surgical methods or a cryogenic method employing liquid nitrogen. Currently, methods used are scalpel (cold steel) surgery, electrodesiccation, and use of liquid nitrogen in cryogenic methods. However, there are a number of significant drawbacks and problems associated with these prior art methods, including, among other things, undue cost, excess time required, complications and the need for expensive storage dewars.
Among the problems associated with the use of liquid nitrogen as a cryogenic agent in heretofore employed cryogenic procedures are (1) a 3-5% evaporation of the liquid nitrogen product while being stored for use, (2) the need for expensive storage dewars for liquid nitrogen generally costing from about $600 to about $2500, (3) expensive delivery systems generally costing from about $700 to about $3000 generally required to spray this cryogen onto the skin and mucous membranes, and (4) occasional permanent hypopigmentation and hypertrophic scarring.
These drawbacks and problems have adversely affected the number of physicians able to perform such operations and the number of patients to receive such treatments for skin lesions.
Among the problems associated with scalpel (cold steel) surgery are (1) bacterial skin infection rates of up to about 18% depending upon, among other things, the sterile technique employed by the operator and heat and humidity of the location of the surgery, (2) hypertrophic scarring which can occur in up to about 25% of patients depending, in general, upon the operator's skill, experience and judgement, and the patient's genetic predisposition to scar, and (3) inefficient use of time. Most scalpel surgery procedures generally require about 25 to 50 minutes to perform. This time is necessitated by the time required for (a) anaesthetizing the treatment area, (b) about 5 minutes waiting period for lidocaine to become optimally effective, (c) time for preparing a sterile operating field, and (d) time for performing the scalpel surgery procedure.
Among the problems associated with electrodesiccation are (1) time consuming need for a local anaesthetic to be applied and become optimally effective and (2) permanent hypertrophic scarring that occurs in a significant percentage of patients undergoing this procedure.
An example of the literature discussing some of these prior art methods and corresponding problems is Skin Surgery, Irwin Epstein and Irwin Epstein, Jr., 6th edition, 1987, W. B. Saunders, Philadelphia, Penna., pages 180-182 which includes pictures of facial hypertrophic scarring following curettage and electrodesiccation.
In U.S. Pat. No. 4,865,028 there is taught a method for therapeutic treatment, such as the removal of warts, by local freezing utilizing a cotton wool bud which has been cooled by means of a liquid cryogenic refrigerant present as a liquid in a pressurized container. The cotton wool bud is provided on the end of a hollow rod or capillary tube which is connected to a sealed aerosol container containing the refrigerant, which boils within the temperature range of 0.degree. C. to -50.degree. C., under the pressure of its own gas phase. According to the method of this patent, the cotton wool bud is filled to its saturation drip point. Because cotton is a loose weave and low density swab of irregular shaped fibers having variable interstices, saturation to the drip point thereof results in a waste of cryogenic agent and can produce a dangerous situation, particularly if the refrigerant is flammable to any extent. Moreover, the inconsistent size and shape of the cotton buds as well as the inconsistent weave produce inconsistent treatment results.
It is therefore an object of this invention to provide an improved method for the treatment of skin lesions that substantially eliminates or avoids the aforesaid drawbacks and problems. A further object of this invention is to produce such a method for treating skin lesions which will be less expensive than procedures heretofore used and thus allow more physicians to perform and patients to receive such treatment at much less cost, and which requires less time involved in the procedure and with less side effects or complications, such as infections, hypertrophic scarring and the like. A still further object of this invention is to provide such an improved method for treatment of skin lesions which does not require expensive storage dewars and no need for expensive delivery devices. An even still further object of this invention is to provide such an improved method for treatment of skin lesions requiring up to or about 1/15th of the time required for traditional scalpel surgery or electrodesiccation and curettage which most physicians currently use to treat such skin lesions. A yet still further object is to provide an improved method for treatment of skin lesions in which the potential for human suffering and permanent disfigurement is substantially eliminated or avoided. Additionally, an object of this invention is to provide an improved process for treatment of skin lesions which is more time-efficient and thus saves physician and patient time involved in the procedure. Another additional object of this invention is to provide an improved method for treatment of skin lesions having significant economical and cosmetic benefit to physicians and patients, and which is portable, i.e. is capable of easily being carried from office to office or office to hospital. A still further additional object of this invention is to provide an improved method for treatment of skin lesions which reduces waste of excess cryogenic agent and substantially eliminates dangerous flammable conditions from occurring. Yet another object of this invention is to provide an improved method for treatment of skin lesions wherein the foam applicator can be produced in any desirable shape and thereby provide improved and consistent treatment results. Another object of this invention is for a synthetic foam applicator to provide pressure to the skin lesion being treated in order to effectively decrease the available "heat sink" to rewarm the skin lesion after treatment.